1. Field of the Invention
The present invention relates to a wavelength tunable semiconductor laser.
2. Description of the Related Art
A wavelength tunable laser, which is disclosed in U.S. Pat. No. 4,896,325, for example, includes a gain region, a phase adjustment region and distributed Bragg reflectors disposed at ends of the device. The gain region and the phase adjustment region are disposed between two distributed Bragg reflectors.